Cloning of the APECED gene provides new insight into human autoimmunity

Phylogeny, Structure, Functions, and Role of AIRE in the Formation of T-Cell Subsets

It is well known that the most important feature of adaptive immunity is the specificity that provides highly precise recognition of the self, altered-self, and non-self. Due to the high specificity of antigen recognition, the adaptive immune system participates in the maintenance of genetic homeostasis, supports multicellularity, and protects an organism from different pathogens at a qualitatively different level than innate immunity. This seemingly simple property is based on millions of years of evolution that led to the formation of diversification mechanisms of antigen-recognizing receptors and later to the emergence of a system of presentation of the self and non-self antigens. The latter could have a crucial significance because the presentation of nearly complete diversity of auto-antigens in the thymus allows for the "calibration" of the forming repertoires of T-cells for the recognition of self, altered-self, and non-self antigens that are presented on the periphery. The central role in this process belongs to promiscuous gene expression by the thymic epithelial cells that express nearly the whole spectrum of proteins encoded in the genome, meanwhile maintaining their cellular identity. This complex mechanism requires strict control that is executed by several transcription factors. One of the most important of them is AIRE. This noncanonical transcription factor not only regulates the processes of differentiation and expression of peripheral tissue-specific antigens in the thymic medullar epithelial cells but also controls intercellular interactions in the thymus. Besides, it participates in an increase in the diversity and transfer of presented antigens and thus influences the formation of repertoires of maturing thymocytes. Due to these complex effects, AIRE is also called a transcriptional regulator. In this review, we briefly described the history of AIRE discovery, its structure, functions, and role in the formation of antigen-recognizing receptor repertoires, along with other transcription factors. We focused on the phylogenetic prerequisites for the development of modern adaptive immunity and emphasized the importance of the antigen presentation system.

Autoimmune Enteropathy: An Updated Review with Special Focus on Stem Cell Transplant Therapy

Autoimmune enteropathy (AIE) is a complex disease affecting both children and adults. Although associated with significant morbidity and mortality, the pathophysiology of the disease and its treatment have not been well characterized. This study aims to review the medical literature available on this rare but clinically significant ailment, to help establish a better understanding of its pathophysiology and enumerate the available diagnostic and treatment modalities. A literature search was conducted on PubMed using key terms related to autoimmune enteropathy and intractable diarrhea, with no restrictions on the date of publication or language. We found a total of 98 reports of AIE published in the form of case reports and case series. The evidence reviewed suggests that AIE is a multifaceted disorder that requires a high index of suspicion in the appropriate clinical setting to be able to make an early diagnosis. Current evidence supports the use of supportive care to correct nutritional and metabolic deficiencies, and immunosuppressives and immunomodulators as directed therapies. Hematopoietic stem cell transplant is an aggressive, but successful curative modality for patients with AIE as part of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome. Cumulative clinical experience with management of AIE has allowed improved outcomes in transplanted and non-transplanted AIE patients even though morbidity and mortality with are still high in patients with this condition. More research is needed to further define the role of new therapies for AIE, and a central registry with participation of multiple institutions might help share and standardize care of patients with this rare but serious condition.

Nuclear Factor-kappaB in Autoimmunity: Man and Mouse

NF-κB (nuclear factor-kappa B) is a transcription complex crucial for host defense mediated by innate and adaptive immunity, where canonical NF-κB signaling, mediated by nuclear translocation of RelA, c-Rel, and p50, is important for immune cell activation, differentiation, and survival. Non-canonical signaling mediated by nuclear translocation of p52 and RelB contributes to lymphocyte maturation and survival and is also crucial for lymphoid organogenesis. We outline NF-κB signaling and regulation, then summarize important molecular contributions of NF-κB to mechanisms of self-tolerance. We relate these mechanisms to autoimmune phenotypes described in what is now a substantial catalog of immune defects conferred by mutations in NF-κB pathways in mouse models. Finally, we describe Mendelian autoimmune syndromes arising from human NF-κB mutations, and speculate on implications for understanding sporadic autoimmune disease.

Update on Aire and thymic negative selection

Twenty years ago, the autoimmune regulator (Aire) gene was associated with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, and was cloned and sequenced. Its importance goes beyond its abstract link with human autoimmune disease. Aire identification opened new perspectives to better understand the molecular basis of central tolerance and self-non-self distinction, the main properties of the immune system. Since 1997, a growing number of immunologists and molecular geneticists have made important discoveries about the function of Aire, which is essentially a pleiotropic gene. Aire is one of the functional markers in medullary thymic epithelial cells (mTECs), controlling their differentiation and expression of peripheral tissue antigens (PTAs), mTEC-thymocyte adhesion and the expression of microRNAs, among other functions. With Aire, the immunological tolerance became even more apparent from the molecular genetics point of view. Currently, mTECs represent the most unusual cells because they express almost the entire functional genome but still maintain their identity. Due to the enormous diversity of PTAs, this uncommon gene expression pattern was termed promiscuous gene expression, the interpretation of which is essentially immunological - i.e. it is related to self-representation in the thymus. Therefore, this knowledge is strongly linked to the negative selection of autoreactive thymocytes. In this update, we focus on the most relevant results of Aire as a transcriptional and post-transcriptional controller of PTAs in mTECs, its mechanism of action, and its influence on the negative selection of autoreactive thymocytes as the bases of the induction of central tolerance and prevention of autoimmune diseases.

Aire Downregulation Is Associated with Changes in the Posttranscriptional Control of Peripheral Tissue Antigens in Medullary Thymic Epithelial Cells

Autoimmune regulator (Aire) is a transcriptional regulator of peripheral tissue antigens (PTAs) and microRNAs (miRNAs) in medullary thymic epithelial cells (mTECs). In this study, we tested the hypothesis that Aire also played a role as an upstream posttranscriptional controller in these cells and that variation in its expression might be associated with changes in the interactions between miRNAs and the mRNAs encoding PTAs. We demonstrated that downregulation of Aire in vivo in the thymuses of BALB/c mice imbalanced the large-scale expression of these two RNA species and consequently their interactions. The expression profiles of a large set of mTEC miRNAs and mRNAs isolated from the thymuses of mice subjected (or not) to small-interfering-induced Aire gene knockdown revealed that 87 miRNAs and 4,558 mRNAs were differentially expressed. The reconstruction of the miRNA–mRNA interaction networks demonstrated that interactions between these RNAs were under Aire influence and therefore changed when this gene was downregulated. Prior to Aire-knockdown, only members of the miR-let-7 family interacted with a set of PTA mRNAs. Under Aire-knockdown conditions, a larger set of miRNA families and their members established this type of interaction. Notably, no previously described Aire-dependent PTA interacted with the miRNAs, indicating that these PTAs were somehow refractory. The miRNA–mRNA interactions were validated by calculating the minimal free energy of the pairings between the miRNA seed regions and the mRNA 3′ UTRs and within the cellular milieu using the luciferase reporter gene assay. These results suggest the existence of a link between transcriptional and posttranscriptional control because Aire downregulation alters the miRNA–mRNA network controlling PTAs in mTEC cells.

Ocular manifestations of autoimmune polyendocrinopathy syndrome type 1

PURPOSE OF REVIEW

The ocular manifestations in autoimmune polyendocrinopathy syndrome type 1 (APS1) are frequent and have a poor prognosis. The phenotype of these APS1-associated ocular features have been recently characterized in molecularly confirmed patients with APS1.

RECENT FINDINGS

Keratopathy and retinopathy can be severe manifestations of APS1. Heterogeneous corneal involvement can be observed, ranging from minimal superficial punctate staining to severe stromal scarring with deep corneal neovascularization. This phenotypic heterogeneity, observed even in patients with identical AIRE mutations, is suggestive of a poor genotype-phenotype correlation. Similarly, in patients with retinopathy, peripheral pigmentary changes are noted in all cases, yet with heterogeneous severity, ranging from isolated patchy atrophy of the retinal pigment epithelium to a retinitis pigmentosa-like fundus. Macular atrophy with vision loss is found in most cases. The severity of ophthalmic findings is uncorrelated to that of systemic manifestations. An autoimmune origin with specific autoantibodies directed against corneal and/or retinal autoantigens is the main mechanism believed to be responsible for the ocular manifestations of APS1.

SUMMARY

Progressive keratopathy and/or retinopathy can lead to severe visual loss and pain in patients with APS1. Although no treatment has shown efficacy regarding the APS1-associated ocular manifestations, ophthalmologic examinations are recommended in these patients.

Population Structure Shapes Copy Number Variation in Malaria Parasites

If copy number variants (CNVs) are predominantly deleterious, we would expect them to be more efficiently purged from populations with a large effective population size (Ne) than from populations with a small Ne. Malaria parasites (Plasmodium falciparum) provide an excellent organism to examine this prediction, because this protozoan shows a broad spectrum of population structures within a single species, with large, stable, outbred populations in Africa, small unstable inbred populations in South America and with intermediate population characteristics in South East Asia. We characterized 122 single-clone parasites, without prior laboratory culture, from malaria-infected patients in seven countries in Africa, South East Asia and South America using a high-density single-nucleotide polymorphism/CNV microarray. We scored 134 high-confidence CNVs across the parasite exome, including 33 deletions and 102 amplifications, which ranged in size from <500 bp to 59 kb, as well as 10,107 flanking, biallelic single-nucleotide polymorphisms. Overall, CNVs were rare, small, and skewed toward low frequency variants, consistent with the deleterious model. Relative to African and South East Asian populations, CNVs were significantly more common in South America, showed significantly less skew in allele frequencies, and were significantly larger. On this background of low frequency CNV, we also identified several high-frequency CNVs under putative positive selection using an FST outlier analysis. These included known adaptive CNVs containing rh2b and pfmdr1, and several other CNVs (e.g., DNA helicase and three conserved proteins) that require further investigation. Our data are consistent with a significant impact of genetic structure on CNV burden in an important human pathogen.

Keratopathy in Autoimmune Polyendocrinopathy Syndrome Type 1

PURPOSE

To report the spectrum of phenotypes in patients with autoimmune polyendocrinopathy syndrome type 1 (APS1)-related keratopathy.

METHODS

In this retrospective observational case series, 6 patients followed for APS1 were included. Data collected included family history, age at presentation, and systemic and ophthalmic manifestations. The 14 coding exons of the autoimmune regulator (AIRE) gene were sequenced.

RESULTS

The age at the onset of keratopathy ranged from 4 to 20 years. The ocular symptoms varied from mild photophobia to severe pain, and visual acuity was from light perception to 20/20 Snellen equivalent. Heterogeneous corneal involvement was observed, ranging from minimal superficial punctate staining to severe stromal scarring with deep corneal neovascularization. The severity of ophthalmic findings was uncorrelated to that of systemic manifestations. The genetic analyses identified 2 novel mutations (c.173C>A in exon 2 and c.892G>T in exon 8) and 4 known mutations (c.62C>T in exon 1, c.415C>T in exon 3, c.1096-1G>A in intron 9, and c.1193delC in exon 10) in the AIRE gene. In patients with identical AIRE mutations, including within a sib-pair, heterogeneous phenotypes were observed.

CONCLUSIONS

Keratopathy can be an early and severe manifestation of APS1, which contributes to the global prognosis of the disease. Its mechanisms remain to be elucidated.

[Induction of central tolerance by the factor Aire: molecular and epigenetic regulation]

The establishment of thymic central tolerance is a critical process to prevent the development of autoimmune diseases. Medullary thymic epithelial cells (mTEC) are essential to this process through the expression of the transcription factor Aire, which controls the transcription of many genes encoding tissue-restricted antigens. Mutations in the Aire gene are responsible for a rare autoimmune disorder called APECED (autoimmune polyendocrinopathy candidiasis ectodermal dystrophy). This review summarizes our current knowledge on the mode of action of Aire at the molecular and epigenetic levels in controlling the expression of tissue-restricted antigens. We also discuss recently described additional roles of this transcription factor in the induction of central T-cell tolerance.

Distribution and medical impact of loss-of-function variants in the Finnish founder population

Exome sequencing studies in complex diseases are challenged by the allelic heterogeneity, large number and modest effect sizes of associated variants on disease risk and the presence of large numbers of neutral variants, even in phenotypically relevant genes. Isolated populations with recent bottlenecks offer advantages for studying rare variants in complex diseases as they have deleterious variants that are present at higher frequencies as well as a substantial reduction in rare neutral variation. To explore the potential of the Finnish founder population for studying low-frequency (0.5-5%) variants in complex diseases, we compared exome sequence data on 3,000 Finns to the same number of non-Finnish Europeans and discovered that, despite having fewer variable sites overall, the average Finn has more low-frequency loss-of-function variants and complete gene knockouts. We then used several well-characterized Finnish population cohorts to study the phenotypic effects of 83 enriched loss-of-function variants across 60 phenotypes in 36,262 Finns. Using a deep set of quantitative traits collected on these cohorts, we show 5 associations (p<5×10⁻⁸) including splice variants in LPA that lowered plasma lipoprotein(a) levels (P = 1.5×10⁻¹¹⁷). Through accessing the national medical records of these participants, we evaluate the LPA finding via Mendelian randomization and confirm that these splice variants confer protection from cardiovascular disease (OR = 0.84, P = 3×10⁻⁴), demonstrating for the first time the correlation between very low levels of LPA in humans with potential therapeutic implications for cardiovascular diseases. More generally, this study articulates substantial advantages for studying the role of rare variation in complex phenotypes in founder populations like the Finns and by combining a unique population genetic history with data from large population cohorts and centralized research access to National Health Registers.

The biophysical and biochemical properties of the autoimmune regulator (AIRE) protein

AIRE (for autoimmune regulator) is a multidomain protein that performs a fundamental function in the thymus and possibly in the secondary lymphoid organs: the regulation, especially in the sense of activation, of the process of gene transcription in cell lines deputed to the presentation of self-antigens to the maturing T lymphocytes. The apoptosis of the elements bearing T-cell receptors with critical affinity for the exhibited self-antigens prevents the escape of autoreactive clones and represents a simple and efficient mechanism of deletional self-tolerance. However, AIRE action relies on an articulated complex of biophysical and biochemical properties, in most cases attributable to single subspecialized domains. Here a thorough review of the matter is presented, with a privileged look at the pathogenic changes of AIRE that interfere with such properties and lead to the impairment in its chief function.

Identification of novel thymic epithelial cell subsets whose differentiation is regulated by RANKL and Traf6

Thymic epithelial cells (TECs) are critical for the normal development and function of the thymus. Here, we examined the developmental stages of TECs using quantitative assessment of the cortical and medullary markers Keratin 5 and Keratin 8 (K5 and K8) respectively, in normal and gain/loss of function mutant animals. Gain of function mice overexpressed RANKL in T cells, whereas loss of function animals lacked expression of Traf6 in TECs (Traf6ΔTEC). Assessment of K5 and K8 expression in conjunction with other TEC markers in wild type mice identified novel cortical and medullary TEC populations, expressing different combinations of these markers. RANKL overexpression led to expansion of all medullary TECs (mTECs) and enlargement of the thymic medulla. This in turn associated with a block in thymocyte development and loss of CD4+ CD8+, CD4+ and CD8+ thymocytes. In contrast, Traf6 deletion inhibited the production of most TEC populations including cortical TECs (cTECs), defined by absence of UEA-1 binding and LY51 expression, but had no apparent effect on thymocyte development. These results reveal a large degree of heterogeneity within the TEC compartment and the existence of several populations exhibiting concomitant expression of cortical, medullary and epithelial markers and whose production is regulated by RANKL and Traf6.

Lymphoid tissue inducer cells: pivotal cells in the evolution of CD4 immunity and tolerance?

PHYLOGENY SUGGESTS THAT THE EVOLUTION OF PLACENTATION IN MAMMALS WAS ACCOMPANIED BY SUBSTANTIAL CHANGES IN THE MAMMALIAN IMMUNE SYSTEM: in particular lymph nodes and CD4 high affinity memory antibody responses co-evolved during the same period. Lymphoid tissue inducer cells (LTi) are members of an emerging family of innate lymphoid cells (ILCs) that are crucial for lymph node development, but our studies have indicated that they also play a pivotal role in the long-term maintenance of memory CD4 T cells in adult mammals through their expression of the tumor necrosis family members, OX40- and CD30-ligands. Additionally, our studies have shown that these two molecules are also key operators in CD4 effector function, as their absence obviates the need for the FoxP3 dependent regulatory T (T(regs)) cells that prevent CD4 driven autoimmune responses. In this perspective article, we summarize findings from our group over the last 10 years, and focus specifically on the role of LTi in thymus. We suggest that like memory CD4 T cells, LTi also play a role in the selection and maintenance of the T(regs) that under normal circumstances are absolutely required to regulate CD4 effector cells.

Lymphoid tissue inducer cells: innate cells critical for CD4+ T cell memory responses?

Lymphoid tissue inducer cells (LTi) are a relatively new arrival on the immunological cellular landscape, having first been characterized properly only 15 years ago. They are members of an emerging family of innate lymphoid cells (ILCs). Elucidation of their function reveals links not only with the ancient innate immune system, but also with adaptive immune responses, in particular the development of lymph nodes and CD4(+) T cell memory immune responses, which on one hand underpin the success of vaccination strategies, and on the other hand drive many human immunologically mediated diseases. This perspective article is not an exhaustive account of the role of LTi in the development of lymphoid tissues, as there have been many excellent reviews published already. Instead, we combine current knowledge of genetic phylogeny and comparative immunology, together with classical mouse genetics, to suggest how LTi might have evolved from a primitive lymphocytic innate cell in the ancestral 500-million-year-old vertebrate immune system into a cell critical for adaptive CD4(+) T cell immune responses in mammals.

Intrinsic and extrinsic control of peripheral T-cell tolerance by costimulatory molecules of the CD28/ B7 family

Positive and negative costimulation by members of the CD28 family is critical for the development of productive immune responses against foreign pathogens and their proper termination to prevent inflammation-induced tissue damage. In addition, costimulatory signals are critical for the establishment and maintenance of peripheral tolerance. This paradigm has been established in many animal models and has led to the development of immunotherapies targeting costimulation pathways for the treatment of cancer, autoimmune disease, and allograft rejection. During the last decade, the complexity of the biology of costimulatory pathways has greatly increased due to the realization that costimulation does not affect only effector T cells but also influences regulatory T cells and antigen-presenting cells. Thus, costimulation controls T-cell tolerance through both intrinsic and extrinsic pathways. In this review, we discuss the influence of costimulation on intrinsic and extrinsic pathways of peripheral tolerance, with emphasis on members of the CD28 family, CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4), and programmed death-1 (PD-1), as well as the downstream cytokine interleukin-1 (IL-2).

Recent insights into the role and molecular mechanisms of the autoimmune regulator (AIRE) gene in autoimmunity

Since many years immunologists have being tried to answer the tantalizing enigma of immunological tolerance. Complex mechanisms in both thymus (central tolerance) and peripheral lymphoid organs (peripheral tolerance) underly lymphocyte tolerance and its maintenance. The genesis of autoimmunity involves environmental and genetic mechanisms, both contributing to the disruption and deregulation of central and peripheral tolerance, allowing autoreactive pathogenetic T and B-cell clones arising. Among genetic factors the autoimmune regulator (AIRE) gene is one of the best candidates to understand the complex scenario of autoimmunity. Autoimmune polyendocrinopathy syndrome type 1 is a rare autosomal recessive disease caused by mutations in the AIRE gene. Therefore, the disorder has certainly been a powerful model to address the question concerning how a tolerant state is achieved or maintained and to explore how it has gone lost in the context of autoimmunity. AIRE has been proposed to function as a 'non classical' transcription factor, strongly implicated in the regulation of organ-specific antigen expression in thymic epithelial cells and in the imposition of T cell tolerance, thus regulating the negative selection of autoreactive T cell clones. A plethora of proposal have been suggested for AIRE's potential mechanism of action, thus regulating the negative selection of autoreactive T cells. In this review recent discoveries are presented into the role and molecular mechanisms of the AIRE protein in APECED and other autoimmune diseases.

[Prevalence of polyglandular autoimmune syndrome in patients with diabetes mellitus type 1]

BACKGROUND AND PURPOSE

The aim of this study was to examine the prevalence of autoimmune antibodies (autoimmune hypophysitis, adrenalitis, thyropathy, pernicious anemia, celiac disease) and clinically relevant endocrine autoimmune disease (AIEK) in patients with type 1 diabetes in the course of 1 year.

PATIENTS AND METHODS

Antibody screening was performed in 139 diabetic patients (age 44 +/- 14 years; years since diagnosis 26 +/- 15 years; duration of diabetes 18 +/- 12 years; body mass index 26 +/- 4 kg/m(2); HbA(1c) 7.5% +/- 1.1% [normal range 4.4-5.9%]) who completed a routine clinic visit in 2003. Patients with pathologically increased antibody titers were further examined regarding the clinically relevant AIEKs. Reexamination was performed 1 year later.

RESULTS

In 2003, 63% of diabetic patients showed at least one pathologically increased antibody titer (2004: 60%). In 32% of the patients, increased antibody titers were clinically inapparent. Apart from diabetes mellitus type 1, in 2003, 31% suffered from other AIEK requiring therapy (2004: +3.6%): 22.3% harbored two additional AIEKs (2004: +2.2%) and 8.6% even > or = 3 AIEKs (2004: +1.5%). The following pathologically increased antibody titers/prevalences of clinically relevant AIEKs were found (in comparison with 2004): increased antithyroid autoantibodies: 47.5% (-0.7%)/autoimmune thyroiditis 24.5% (+2.8%) and Graves' disease 4.3% (+0.7%), respectively; adrenal cortex autoantibodies 0.7% (+1.5%)/Addison's disease 1.4% (+/-0), gliadin peptide antibodies and IgA to tissue transglutaminase, respectively: 18.7% (-5.0%)/celiac disease 1.4% (+0.8%), parietal cell antibodies: 15.8% (+7.2%)/pernicious anemia 7.2% (+1.4%), hypophysitis 0.7% (+/-0), hypogonadism 0.7% (+/-0). All new AIEK manifestations in 2004 had had an at least tenfold increased antibody titer in 2003. Comparing patients with and without polyglandular autoimmune syndrome (PAS), no difference in age (43 +/- 14 vs. 46 +/- 13 years), duration of diabetes (17 +/- 13 vs. 18 +/- 12 years), and HbA1c (7.3% +/- 0.9% vs. 7.6% +/- 1.1%) could be found.

CONCLUSION

In this study, more than half of the patients with diabetes mellitus type 1 had at least one pathologically increased antibody titer apart from diabetes without clinical sign of an additional AIEK. 31% of patients with increased antibodies presented with symptoms of another AIEK (increase by 3.6% within 1 year). Patients with diabetes mellitus type 1 should be screened for other AIEKs. Thyropathy had the greatest prevalence and increased by 3.5% within 1 year's time.

The tumor necrosis factor family receptors RANK and CD40 cooperatively establish the thymic medullary microenvironment and self-tolerance

Medullary thymic epithelial cells (mTECs) establish T cell self-tolerance through the expression of autoimmune regulator (Aire) and peripheral tissue-specific self-antigens. However, signals underlying mTEC development remain largely unclear. Here, we demonstrate crucial regulation of mTEC development by receptor activator of NF-kappaB (RANK) and CD40 signals. Whereas only RANK signaling was essential for mTEC development during embryogenesis, in postnatal mice, cooperation between CD40 and RANK signals was required for mTEC development to successfully establish the medullary microenvironment. Ligation of RANK or CD40 on fetal thymic stroma in vitro induced mTEC development in a tumor necrosis factor-associated factor 6 (TRAF6)-, NF-kappaB inducing kinase (NIK)-, and IkappaB kinase beta (IKKbeta)-dependent manner. These results show that developmental-stage-dependent cooperation between RANK and CD40 promotes mTEC development, thereby establishing self-tolerance.

Autoimmunity and persistent viral infection: two sides of the same coin?

Organ specific autoimmunity follows induction and perpetuation of cell mediated immune effector responses to antigens expressed by somatic cells of the target organ, and clearance of persistent viral infection requires a similar immune response. Research on regulators of innate and adaptive immunity that hinder clearance of viral infection may therefore shed light on genetic factors predisposing to organ specific autoimmunity. This article discusses Ian Mackay's interests in autoimmunity when I was his assistant physician, and their influence on my group's subsequent research on persistent viral infection.

Prospective familial assessment in dilated cardiomyopathy: cardiac autoantibodies predict disease development in asymptomatic relatives

BACKGROUND

In autoimmune disorders, circulating autoantibodies identify healthy relatives at risk years before clinical presentation. Healthy relatives of patients with dilated cardiomyopathy (DCM) who have echocardiographic changes, including left ventricular enlargement or depressed fractional shortening at baseline, have increased medium-term risk for DCM development. Approximately one third of relatives have serum anti-heart autoantibodies (AHAs) at baseline; we intended to assess their potential role in predicting DCM development.

METHODS AND RESULTS

Baseline evaluation, including electrocardiography, echocardiography, and AHA, was performed in 592 asymptomatic relatives of 169 consecutive DCM patients (291 males and 301 females; mean age 36+/-16 years). Relatives were classified in accordance with published echocardiographic criteria; those who did not have DCM were followed up (median of 58 months). DCM among relatives was diagnosed by echocardiography at follow-up. Of the 592 individuals evaluated, 77% were assessed as normal, 4.4% as having DCM, and 19% as possibly affected on the basis of depressed fractional shortening without ventricular dilatation in 17 and left ventricular enlargement without systolic dysfunction in 94. Five-year follow-up of 311 relatives revealed that 26 had progressed (13 to DCM, 11 to left ventricular enlargement, and 2 to depressed fractional shortening). Relatives who developed DCM were more frequently AHA-positive than those who did not (69% versus 37%, P=0.02). Five-year probability of progression to DCM, among normal or possibly affected relatives, was higher in AHA-positive cases (P=0.03). By Cox regression, positive AHAs at baseline were independent predictors of progression (RR 2.26, CI 1 to 5.1, P=0.03).

CONCLUSIONS

Among healthy relatives of DCM patients, AHAs are independent predictors of disease development within 5 years.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome with renal failure: impact of posttransplant immunosuppression on disease activity

CONTEXT

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder caused by mutations in the gene AIRE (autoimmune regulator). APECED affects mainly endocrine organs resulting in hypoparathyroidism, adrenocortical failure, diabetes mellitus, hypogonadism, and hypothyroidism. Nonendocrine organ manifestations are autoimmune hepatitis, vitiligo, pernicious anemia, exocrine pancreatic insufficiency, and alopecia. APECED's first manifestation generally is mucocutaneous candidiasis presumably related to T cell dysfunction.

PATIENT

A 5-yr-old Iranian girl presented first with pernicious anemia, exocrine pancreatic insufficiency, and nail candidiasis. She had renal dysfunction due to chronic interstitial nephritis (CIN), which progressed to end-stage renal failure. She was transplanted 1 yr later. Common causes of CIN were excluded. APECED was suspected first because she developed progressively hypoparathyroidism, adrenocortical failure, glucose intolerance, and hypothyroidism.

RESULTS

Genetic analysis revealed a large homozygous deletion (g.424_2157del1734), spanning exons 2-4, in the AIRE gene. The predicted protein, if it is produced, has only 44 amino acids (exon 1) in common with the wild-type protein. Immunosuppression after the first renal transplant included prednisone, azathioprine, and cyclosporine A. Multiple acute rejection episodes occurred. Chronic rejection resulted in lost graft and she was retransplanted 2 yr later. Surprisingly, all APECED-related symptoms including candidiasis and autoantibody levels decreased, presumably due to the reinforced immunosuppression (tacrolimus, mycophenolate mofetil, prednisone).

CONCLUSIONS

This is the first report of an APECED patient with CIN resulting in end-stage renal failure. Clinical and biological improvement was observed under posttransplant multidrug immunosuppression including tacrolimus and mycophenolate mofetil.

[Alopecia totalis, hypotension and erectile dysfunction in a 34 year old patient. Difficult clarification of a common cause]

The occurrence of both autoimmune endocrinopathies and endocrinopathies caused by other reasons is called polyglandular autoimmune syndrome (PAS-syndrome). In a 34 years old man with weakness, weight loss and erectile dysfunction we found low cortisol caused by an autoimmune adrenalitis and low testosterone caused by a hypophysitis with impaired gonadotropin secretion. Thyroid autoantibodies and islet cell autoantibodies without any hormone deficiencies were further signs of a broad endocrine autoimmune syndrome. In the following 11 years the patient developed three autoimmune disorders: paradrenal glandular insufficiency, hypogonadism caused by hypophysitis, Diabetes mellitus type 1. In the same time several non endocrine autoimmune diseases became manifest: alopecia totalis, vitiligo, retrobulbar neuritis and keratoconjunctivitis.

The development of mouse APECED models provides new insight into the role of AIRE in immune regulation

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy is a rare recessive autoimmune disorder caused by a defect in a single gene called AIRE (autoimmune regulator). Characteristics of this disease include a variable combination of autoimmune endocrine tissue destruction, mucocutaneous candidiasis and ectodermal dystrophies. The development of Aire-knockout mice has provided an invaluable model for the study of this disease. The aim of this review is to briefly highlight the strides made in APECED research using these transgenic murine models, with a focus on known roles of Aire in autoimmunity. The findings thus far are compelling and prompt additional areas of study which are discussed.

A worm's eye view of the immune system: consequences for evolution of human autoimmune disease

Humans and the many parasites that we can host have co-evolved over millions of years. This has been compared to an arms race in which the immune armoury of the human has evolved to deal with potential pathogens and the pathogen has evolved strategies to evade, and in some cases use, the immune system of the human host. Recently, there have been marked changes in the exposure of individuals in the developed world to both microorganisms and metazoan parasites, so the immune stimuli such organisms provide no longer have a role in our lives. As we discuss here, this is a marked perturbation, and the absence of the associated immunomodulation might have led to the increased emergence of autoimmune diseases.

AIRE and APECED: molecular insights into an autoimmune disease

Mutations in the autoimmune regulator (AIRE) protein are the causative factor in development of the human disease autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). In mice, the absence of the analogous protein aire influences ectopic expression of peripheral tissue antigens in thymic medullary epithelial cells (MECs), resulting in the development of an autoimmune disorder similar to APECED and establishing aire/AIRE as an important player in the induction of central tolerance. However, the molecular mechanism of AIRE's function, in particular its ability to specifically control the expression of peripheral tissue antigens in MECs, is still unclear. Here, we review current evidence relating to the molecular mechanism of AIRE.

Update on primary immunodeficiency: defects of lymphocytes

The recent identification of the genes involved in many primary immunodeficiency disorders has led to a significant increase in our understanding of the pathogenesis of these defects. Many of these disorders share a clinical phenotype with common features such as recurrent infections, chronic inflammation, and autoimmunity. Although some of these immune defects have mild presentations and better outcomes, others result in severe infections and significant morbidity and mortality. For these, early diagnosis and treatment are critical. This review provides an overview of the genetic defects and clinical features of primary immune deficiencies due to defects in lymphocytes.

The Finnish Disease Heritage III: the individual diseases

This article is the third and last in a series entitled The Finnish Disease Heritage I-III. All the 36 rare hereditary diseases belonging to this entity are described for clinical and molecular genetic purposes, based on the Finnish experience gathered over a period of half a century. In addition, five other diseases are mentioned. They may be included in the list of the "Finnish diseases" after adequate complementary studies.

12. Primary immunodeficiency diseases

Although primary immunodeficiency disorders are relatively rare, intensive investigation of these disorders has yielded a great wealth of understanding of basic immunologic mechanisms in host defense, inflammation, and autoimmunity. These advances have led to important developments for the treatment not only of the primary immunodeficiencies but also for patients with secondary immunocompromised states, autoimmune disorders, hypersensitivity, graft rejection, and graft versus host disease. Correction of a form of severe combined immunodeficiency represents the first true success of human gene therapy. This review introduces the major clinical manifestations of primary immunodeficiency disorders, along with descriptions of essential elements of the pathophysiology of those disorders that have been defined at the molecular level. Key concepts in treatment are also presented. It is critical for the practicing primary care provider and allergist to maintain an index of suspicion for immunodeficiency. Early diagnosis offers the best opportunity for reduced morbidity and survival and is critical for accurate genetic counseling.

Solitary human endogenous retroviruses-K LTRs retain transcriptional activity in vivo, the mode of which is different in different cell types

Solitary long terminal repeats (LTRs) of human endogenous retroviruses (HERVs), tens of thousands of which are spread all over the genome, contain a variety of potential transcription regulatory elements. Information on transcriptional behavior of individual solitary LTRs, however, is limited. We studied the transcriptional activity of several individual HERV-K LTRs in a variety of tissues and cell lines. The RT-PCR technique targeted at specific amplification of the U3 or U5 regions of individual LTRs together with their unique genomic flanks was used to estimate the content of each region in the transcripts. An unequal abundance of the U3 and U5 regions of the transcripts of the same LTR in different cells and tumors was observed. Each LTR is transcribed differently in different cells or tissues, and transcriptional behavior of different LTRs was different in the same cell line or tissue. The transcriptional status of LTRs varies in response to mitogenic and stress factors and in tumor tissues compared to normal counterparts. The LTRs thus seem to be the subjects of specific transcription regulation. The data obtained indicate that an appreciable fraction of the LTRs retained regulatory potential throughout millions of years of evolution and thus may contribute to the overall transcription regulatory network.

Corneal pathology and outcome of keratoplasty in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED)

BACKGROUND

Disabling, chronic, persistent keratoconjunctivitis is an essential ocular manifestation in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED).

PURPOSE

Because of the paucity of previous studies our aim is to describe the main histopathological features of the keratopathy and to report the long-term outcome of corneal grafting.

MATERIAL

Four corneal buttons obtained at keratoplasties. Two patients with clinical follow-up data of 30 years.

RESULTS

The corneal epithelium showed a severe atrophy with even areas of incipient epidermalization. The Bowman's membrane was destroyed. The anterior corneal stroma was replaced by vascularized scar tissue with areas of chronic inflammatory cell infiltration consisting mainly of lymphocytes and plasma cells. The posterior corneal stroma, the Descemet's membrane and the endothelium were normal. Rejection occurred after each keratoplasty. The last visual acuity of the first patient was finger counting of the right eye and 0.3 of the left eye and of the second patient 0.08 of both eyes.

CONCLUSION

In chronic keratopathy of APECED the anterior corneal layers, the epithelium, the Bowman's membrane and the anterior corneal stroma are affected while the posterior cornea appears normal. As after keratoplasty rejection may be expected, its prevention and management need intensive attention.

Autoimmune hemolytic anemia in a patient with autosomal dominant chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis is a heterogeneous immunodeficiency syndrome characterized by recurrent candidal infections of the skin, nails, and mucous membranes. The syndrome can be associated with autoimmune conditions, especially endocrine disorders. Typically, inheritance is autosomal recessive, and abnormal T-cell-mediated immunity is thought to be the underlying deficit. We describe a 27-year-old man with chronic mucocutaneous candidiasis inherited in an autosomal dominant fashion, in whom both lymphocyte blastogenesis and delayed-type skin reactivity to Candida antigens were normal. Notable features of the case include autoimmune hemolytic anemia, probable hypoparathyroidism, and hypogonadal hypogonadism.

The autoimmune regulator protein has transcriptional transactivating properties and interacts with the common coactivator CREB-binding protein

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy, caused by mutations in the autoimmune regulator (AIRE) gene, is an autosomal recessive autoimmune disease characterized by the breakdown of tolerance to organ-specific antigens. The 545 amino acid protein encoded by AIRE contains several structural motifs suggestive of a transcriptional regulator and bears similarity to cellular proteins involved in transcriptional control. We show here that AIRE fused to a heterologous DNA binding domain activates transcription from a reporter promoter, and the activation seen requires the full-length protein or more than one activation domain. At the structural level AIRE forms homodimers through the NH(2)-terminal domain, and molecular modeling for this domain suggests a four-helix bundle structure. In agreement, we show that the common transcriptional coactivator CREB-binding protein (CBP) interacts with AIRE in vitro and in yeast nuclei through the CH1 and CH3 conserved domains. We suggest that the transcriptional transactivation properties of AIRE together with its interaction with CBP might be important in its function as disease-causing mutations almost totally abolish the activation effect.

The genetics of Hashimoto's disease

Despite strong epidemiologic evidence in favor of a genetic component in the etiology of HT, few hereditary risk factors have been consistently identified. These factors include the HLA and CTLA-4 genes. The mechanisms by which these genes confer increased susceptibility to HT are unclear. The identification of these genes has failed to explain completely the large hereditary effect observed in families of patients. More substantial genetic determinants must be hidden in the folds of the human genome and will most likely be detected in the near future. The powerful approach of linkage analysis will be supported by advancements in the description of the human genome and by technologic improvements in the ability to process large amounts of biologic data. Knowledge of such determinants will provide predictive tools to be used on clinical grounds and invaluable insight into the pathogenesis of this puzzling disease.

Genetic analysis of the influence of pertussis toxin on experimental allergic encephalomyelitis susceptibility: an environmental agent can override genetic checkpoints

Pertussis toxin (PTX) is a potent ancillary adjuvant used to elicit several different autoimmune diseases, including experimental allergic encephalomyelitis (EAE). To delineate the genetics of PTX effect in EAE, we mapped EAE-modifying (eae-m) loci in cohorts of backcross mice immunized with and without PTX. In this study, we analyzed the genetic basis of EAE susceptibility and severity and the intermediate phenotypes of mononuclear cell infiltration, suppuration, and demyelination. In animals immunized with PTX, one major locus, eae9, controls disease susceptibility and severity. Eae9 also regulates the extent of mononuclear cell infiltration of the spinal cord in male mice. Without PTX, five eae-m loci were noted, including three new loci in intervals on chromosomes 8 (eae14), 10 (eae17), and 18 (eae18). Taken together, these results suggest that eae9 controls the effects of PTX in EAE susceptibility, and is capable of overriding the other genetic checkpoints in the pathogenesis of this disease.